The present invention generally relates to the field of intrusion detection systems, and more particularly to a system that uses temporal, contemporaneously generated outputs of multiple sensors configured in one or more sensor arrays to detect perturbations in an environment.
U.S. Pat. No. 5,202,661 describes a system for detecting an intrusion within an environment. Such system employs sensors located at fixed locations within the environment and sensors deployed on mobile platforms which patrol throughout the environment. A computer provides instructions to the mobile platforms so that they may be directed to travel along predetermined routes and be rapidly deployed to any region in the environment where a fixed sensor detects a perturbation which may correspond to an intrusion. The computer also receives the outputs of the fixed and mobile sensors and then determines a sum of weighting factors associated with the outputs of both the fixed and mobile sensors. The weights assigned to the sensor outputs are "fused" so that the sum is uninfluenced by detection of any of the traveling mobile platforms by the fixed sensors. The sum is compared to a reference whereupon the computer provides an output signal to enable an alarm system if the sum exceeds a reference value. The sum of weighting factor is based on the outputs of the sensors which are generated at one particular instant in time. In other words, the process implemented in the computer described in the '661 system uses a "snapshot" of data to determine the sum of weighting factors. Thus, in such system, the sum of weighting factors is not based on the history of the sensor outputs. However, an historical analysis of the sensor outputs generated over some time interval could provide useful information. For example, the sensors may generate outputs over time which yield a series of sums of weighting factors each based on evaluations of contemporaneously generated data that are less than some predetermined threshold limit having a reasonable probability of corresponding to an intrusion within the environment, whereas the same data considered collectively over a finite period of time may reveal the likelihood of an intrusion. Therefore, there is a need for an intrusion detection system that uses sensor data generated over a period of time to increase the sensitivity of an intrusion detection system without a concomitant increase in nuisance alarms.